Sub 35

So, I had my follow-up heart scans yesterday after nearly 7 weeks of no recorded avg HR over ~110bpm (usually <105bpm) and no run over 60mins. I've been averaging about 40k per week for the period with pace dropping from 4:45/km down to 6:00/km (or slower) most recently.

The good news is that the volume of my left atrium has decreased from 46mL/m2 to 40mL/m2 which means I'm at a much lower risk of atrial fibrillation, and shows that the size of the atrium is definitely an adaptation to my training (vs. being some other medical condition). The not so good news is that it's still classified as 'severely abnormal', although <40mL/m2 would only be 'moderately abnormal' so I'm not far off

Now... the really interesting thing is what happened when I went for a run today and pushed a little. After the usual 100-110bpm start I tried 2x 2k pretty hard (roughly 5k 'all out' effort) and I recorded a new highest Max HR of 180bpm! In the second 2k I was at 175+ for well over 5 mins.

Consider that in 10 years of using HR monitors I've only once seen a HR over 175, and that was just for a few seconds at the top of a hill in a race (and with optical HR which makes it debatable). At the end of the marathon in Oct I was wearing a strap and hit a Max of 172 for the last 5 seconds crossing the line. In the 15:54 5k in Sept I never went over 170bpm.

It's probably too early to say whether the ability to reach and sustain higher heart rates is related to the smaller atrial volume but it seems likely. If it is indeed the case then I'm wondering if I can develop this "new type of fitness" where I'm able to sustain higher heart rates, and therefore run faster with a lower atrial volume and lower risk of AFib That's the hypothesis anyway...

The other interesting thing is that the 2ks today really weren't that slow... 6:55 and 6:38, despite literally nothing more than a jog in 7 weeks!! That tells me I've probably still got some de-conditioning to go before I reach rock-bottom fitness, so hopefully I can get the atrium even smaller.

That said - the plan now is to take another 6 weeks of very light training (mostly 100-110bpm) to see if I can bring the atrium down to the moderate range.

After that I'm hoping I can adopt a new training style where I mostly do super low heart rate (although still get decent mileage in so the muscles/bones etc. are strong) and then supplement this with sessions of v. high heart rate (for short periods of time) (e.g. the 2k and 1k's).

Hi Jamie, one of the aspects that count a lot in a runner's favour, is experience.

Each year one should develop to a new level and 'muscle memory' plays a large part in being able to run at a higher level on 'little or no' training

avoiding injury and sickness and achieving consistency is what assists athletes the most.

over the years of training, the rule of thumb for easy runs in the early stages of training is to be able to run as easy as possible. In giving advice on the forums, the advice has always been to keep the pulse around 120 to 140 bpm, with the intention that when the athlete begins to train on the 10k programs (for example) their easy runs will be at a faster pace naturally but still the equivalent pulse rate.

Runners (athletes) unfortunately often do not have the patience to run easy (or at lower pulses) but instead continually want to know whether they rounding off into shape. Which can often be to their disadvantage.

Hopefully this is easily understandable, as often it is difficult to put things across via the forums

Yes I've definitely always struggled to keep easy runs 'easy' but I think this off period (as well as the heart complications) have given me a valuable new perspective. I also think that 120-140 for me is more like 110-130 taking my personal physiology into account.

Continuing to enjoy the off period and some cold Swedish weather over Xmas. I'm keeping runs <110bpm and <1hr but have been dropping a fast 1k every now and then to rev the engine (often ~3:00/km and HR well up in the 170's).

Aim to start training properly towards the London Marathon in late Jan (I have a sub elite start again) once the final heart tests are complete. I'm managing to keep mileage around 50-70k and weight <78kg so hopefully I'll be able to spring back fast.